books.google.com - Like a slick, gray torpedo, a dolphin breaks the water&#39;s surface and leaps into a graceful arc. Its shiny skin glistens in the sunlight, just before it dives deeply again. Marine and river dolphins are highly social mammals that live in groups called schools in oceans and rivers. While many people...https://books.google.com/books/about/Dolphins.html?id=5Buh9FtAG8AC&utm_source=gb-gplus-shareDolphins

Dolphins

Like a slick, gray torpedo, a dolphin breaks the water's surface and leaps into a graceful arc. Its shiny skin glistens in the sunlight, just before it dives deeply again. Marine and river dolphins are highly social mammals that live in groups called schools in oceans and rivers. While many people are fascinated with dolphins, humans also have caused them harm. Fishing practices once decreased the number of marine dolphins. River dolphins are greatly affected by the pollution created by humans. Yet many people are working to protect dolphins and their natural habitats. Learn more in this edition of Nature Watch.

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About the author (2007)

Sally M. Walker's many award-winning books bring history and science alive for young readers. Her books include the Robert F. Sibert Medal winner "Secrets Of A Civil War Submarine: Solving the Mysteries of the H. L. Hunley" and the Revolutionary War story "The 18 Penny Goose" (an I Can Read Book). Ms. Walker lives in DeKalb, Illinois.